21286564 has 18 divisors (see below), whose sum is σ = 40338690. Its totient is φ = 9824256.

The previous prime is 21286543. The next prime is 21286579. The reversal of 21286564 is 46568212.

It can be written as a sum of positive squares in 3 ways, for example, as 52900 + 21233664 = 230^2 + 4608^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15069 + ... + 16420.

Almost surely, 2^21286564 is an apocalyptic number.

It is an amenable number.

21286564 is a deficient number, since it is larger than the sum of its proper divisors (19052126).

21286564 is a wasteful number, since it uses less digits than its factorization.

21286564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31519 (or 31504 counting only the distinct ones).

The product of its digits is 23040, while the sum is 34.

The square root of 21286564 is about 4613.7364467425. The cubic root of 21286564 is about 277.1416861719.

The spelling of 21286564 in words is "twenty-one million, two hundred eighty-six thousand, five hundred sixty-four".